Direct and inverse scattering problems for quasi-linear biharmonic operator in 3D

Abstract. We consider direct and inverse scattering problems for three-dimensional biharmonic operator $Hu = ∆^2u + Vu$, where $∆$ is the Laplacian and $V$ is a scalar valued perturbation. The scattering problem for this operator is given as a partial differential equation $Hu = k^4u$, with a parameter $k$. In the direct scattering problem, our goal is to find the solution $u$ while the perturbation (V\) is known. We also assume that the solution $u$ can be written as a sum of two functions $u_{0}$ and $u_{sc}$, where $u_{0}$ is a plane wave and $u_{sc}$ is an outgoing wave in the sense that it satisfies to the Sommerfeld radiation conditions at the infinity. Our approach in this text is to first modify the partial differential equation into an integral equation by using the fundamental solution. Next, we show that this integral equation is solvable, and it has a unique solution. Finally, we prove two main results of this text; an asymptotic formula for the solution with large values of $x ∈ \mathbb{R}^3$ and Saito’s formula. The asymptotic behaviour of the solution leads us to defining the scattering amplitude. In the inverse scattering problem, the goal is to gather some information about the unknown perturbation V while the behaviour of the function u is known. With Saito’s formula we obtain two corollaries regarding the inverse scattering problem, namely uniqueness and a representation formula for the function $V(x, 1)$, when the scattering amplitude is known. We end the text by first defining the inverse Born approximation for both full scattering data and backscattering data. We also discuss some results that have been obtained previously with this approach

The Praised, The Loved, The Deplored, The Forgotten : A View into the Wide History of Finnish Games

The history of Finnish games is diverse. It consists not only of commercially successful digital games or board game classics that have knit together generations. Finnish game history is multifaceted both in terms of technologies and execution, as well as content and impact. The reception of games varies: some are highly praised, others become dearly loved, some are deplored and many will simply become forgotten. A game is a versatile format for a variety of works, by different creators and for different types of players.Games are valuable fixtures of cultural histories around the globe. Finnish games are in a precious role in the cultural heritage of Finland. This book offers only a small sample of games. The idea for the book was conceived during an exhibition organised in a local museum during the Nordic DiGRA 2012 conference, Tampere Finland. Four researchers and roughly 20 students joined efforts to build an exhibition to introduce foreign visitors to local games. Game developers, journalists, historians and collectors lent a helping hand in putting everything together. The multiform exhibition reflected the different backgrounds of the members of the team – we ended up opening a diverse view towards Finnish games. Although the exhibition was open only for a short time, the success surpassed all expectations. The work conducted for the exhibition has been updated for this book, and it has served as a basis for the Finnish Museum of Games opened in 2016. Game history is common knowledge, but not always easy to access. It is time to put more effort in recording the history for future generations as well as to trace the paths already forgotten. Games cannot, however, be understood simply by reading – they must be experienced. Hopefully this book will show a guiding light towards understanding games in a wider spectrum and bring everyone closer to the actual experiences

Cnidoma de los tentáculos de la anémona de mar Metridium senile (Linnaeus, 1761) (Cnidaria: Anthozoa)

Tentacle cnidae of Metridium senile (Linnaeus, 1761) were examined by light microscopy. In addition to spirocysts, feeding-tentacles had 3 nematocyst categories grouped into medium and small size-classes, including 5 types. Spirocysts dominated, especially distally, followed by medium b-mastigophores. The density of cnidae decreased towards the tentacle base. Early cnidoblasts were numerous on the tentacle tip. Late cnidoblasts appeared in a moderate number on the mid-tentacle. Catch-tentacles, found in two Metridium specimens, had a maturity gradient of isorhizas and gland cells along their length. Their tip had two distinct types of mature isorhizas in great numbers and large gland cells, but lacked spirocysts. Mature isorhizas and gland cells decreased in number towards the tentacle base. On the mid-tentacle differentiating ages of isorhizas were numerous. Ordinary feeding-tentacle cnidae, abundant at the tentacle base, decreased in number distally along the tentacle.El cnidoma de los tentáculos de Metridium senile (Linnaeus, 1761) se examinó mediante microscopio óptico. Además de espirocistos, los tentáculos tenían 3 categorías de nematocistos agrupados en clases de talla medianas y pequeñas, incluyendo 5 tipos. Los espirocistos fueron dominantes, en particular distalmente, seguidos por b-mastigióforos medios. La densidad de cnidoma decreció hacia la base del tentáculo. En la punta del tentáculo fueron abundantes los cnidoblastos jóvenes. Los cnidoblastos avanzados aparecieron en número moderado a mitad del tentáculo. Los tentáculos hallados en dos especímenes de Metridium presentaron un gradiente de madurez de isorhizas y células glandulares a lo largo de su longitud. La punta tenía dos tipos distintos de isorhizas maduras en gran número y grandes células glandulares, pero les faltaban espirocistos. Las isorhizas maduras y las células glandulares disminuyeron en número hacia la base del tentáculo. A mitad del tentáculo, se observaron numerosas isorhizas de diferentes edades. Los cnidocistos de los tentáculos, abundantes en la base del tentáculo, disminuyeron en número distalmente a lo largo del tentáculo

Designing “Game Idea Generation” Games

This paper introduces brainstorming games developed for the use of game designers. Three games designed especially for generating new game ideas were developed in the GameSpace project, which studies methods for design and evaluation of casual mobile multiplayer games. GameSpace idea generation games have been developed through an iterative process in collaboration with the end users: game industry professionals. According to our workshop experiences and tentative results from a pilot study, idea generation games can be successful devices for the creative work of game designers. Game- based idea generation techniques provide an easily facilitated, focused yet playful setting for coming up with new ideas. However, our experiences indicate that idea generation games feature special challenges that must be taken into consideration when designing such games

"An Adapt-or-Die Type of Situation": Perception, Adoption, and Use of Text-To-Image-Generation AI by Game Industry Professionals

Text-to-image generation (TTIG) models, a recent addition to creative AI, can generate images based on a text description. These models have begun to rival the work of professional creatives, and sparked discussions on the future of creative work, loss of jobs, and copyright issues, amongst other important implications. To support the sustainable adoption of TTIG, we must provide rich, reliable and transparent insights into how professionals perceive, adopt and use TTIG. Crucially though, the public debate is shallow, narrow and lacking transparency, while academic work has focused on studying the use of TTIG in a general artist population, but not on the perceptions and attitudes of professionals in a specific industry. In this paper, we contribute a qualitative, exploratory interview study on TTIG in the Finnish videogame industry. Through a Template Analysis on semi-structured interviews with 14 game professionals, we reveal 12 overarching themes, structured into 49 sub-themes on professionals' perception, adoption and use of TTIG systems in games industry practice. Experiencing (yet another) change of roles and creative processes, our participants' reflections can inform discussions within the industry, be used by policymakers to inform urgently needed legislation, and support researchers in games, HCI and AI to support the sustainable, professional use of TTIG to benefit people and games as cultural artefacts.Comment: 32 pages (incl. appendix), 3 figures, 4 tables. Coding template (31 pages, 10 tables), study invitations (email, social media) and pre-study survey provided as supplementary (ancillary) material. Accepted with minor revisions at ACM CHI Play 202

TWO-DIMENSIONAL INVERSE SCATTERING FOR QUASI-LINEAR BIHARMONIC OPERATOR

The subject of this work concerns the classical direct and inverse scattering problems for quasi-linear perturbations of the two-dimensional biharmonic operator. The quasi-linear perturbations of the first and zero order might be complex-valued and singular. We show the existence of the scattering solutions to the direct scattering problem in the Sobolev space W-infinity(1)(R-2). Then the inverse scattering problem can be formulated as follows: does the knowledge of the far field pattern uniquely determine the unknown coefficients for given differential operator? It turns out that the answer to this classical question is affirmative for quasi-linear perturbations of the biharmonic operator. Moreover, we present a numerical method for the reconstruction of unknown coefficients, which from the practical point of view can be thought of as recovery of the coefficients from fixed energy measurements.Peer reviewe

Formación de los dardos en los nematocistos de la anémona de mar Metridium senile (Linnaeus, 1761) (Cnidaria: Anthozoa)

In examining large acontia b-mastigophore and p-amastigophore nematocysts of the sea anemone Metridium senile (Linnaeus, 1761) darts were observed by interference-contrast light microscopy (LM) and scanning electron microscopy (SEM). The darts consist of closely packed spines detached from the shafts, still in three helical rows. Their spines form a hollow cylinder with a sharp tip and indented base, its width similar to that of an undischarged shaft but varying in length. b-mastigophore darts were more common than those of p-mastigophores and many were longer.El examen mediante microscopía de contraste de fases (LM) y microscopio electrónico de barrido (MEB) de los grandes nematocistos acontios b-mastigóforos y p- amastigóforos de la anémona de mar Metridium senile (Linnaeus, 1761) permitió la observación de dardos. Los dardos consisten en espinas fuertemente empaquetadas desli- gadas de la punta del dardo, todavía en tres hileras helicoidales. Sus espinas forman un cilindro hueco con una punta afilada y una base no dentada, su anchura es similar a la de la punta de un dardo no descargado, pero varían en longitud. Los dardos b-mastigióforos fueron más frecuentes que los de p-mastigióforos y muchos de ellos fueron más largos

Nematocistos acontia y mesentéricos de la anémona de mar Metridium senile (Linnaeus, 1761) (Cnidaria: Anthozoa)

Acontia and mesentery nematocysts of Metridium senile (Linnaeus, 1761) are described from interference- contrast light micrographs (LMs) and scanning electron micrographs (SEMs). The acontia have 2 nematocyst categories grouped into small, medium and large size-classes, including 5 types: of these, large b-mastigophores and large p-amas- tigophores are the largest and most abundant. Mesenterial tissues, characterised by small p-mastigophores and medium p-amastigophores, have 3 nematocyst categories grouped as small and medium, including 6 types. Attention is given to nematocyst maturation, especially to the differentiation of the shaft into proximal and main regions as helical folding of the shaft wall proceeds. Groups of differentiating nematoblasts occur along acontia, and near the junction between acontia and mesenterial filaments. Nematoblasts are sparsely found throughout mesenterial tissues.Los acontios y los nematocistos de los mesenterios de Metridium senile (Linnaeus, 1761) se describen a partir de microfotografías de contraste-interferencia (LMs) y de microscopio electrónico de barrido (MEB). Los acontios tienen dos categorías de nematocistos agrupados en clases de talla, pequeños, medianos y grandes, incluyendo 5 tipos: de ellos, los mas grandes y abundantes son los b-mastigioforos grandes y los p-amastigióforos grandes. Los tejidos mesentéricos, caracterizados por pequeños p-mastigióporos y medianos p-amastigióforos, tienen 3 categorías de nematocistos agrupadas como pequeñas y medias, incluyendo 6 tipos. Se presta atención a la maduración de los nematocistos, especialmente a la diferenciación de los dardos en las regiones proximales y principales como plegamientos helicoidales de las paredes del dardo. A lo largo de acontia, y cerca de la unión entre los filamentos de acontia y filamentos mesentéricos aparecen grupos de nematoblastos en diferenciación. Los nematoblastos están escasamente representados en todos los tejidos mesentéricos

The History of Quantum Games

In this paper, we explore the historical development of playable quantum physics related games (\textit{\textbf{quantum games}}). For the purpose of this examination, we have collected over 260 quantum games ranging from commercial games, applied and serious games, and games that have been developed at quantum themed game jams and educational courses. We provide an overview of the journey of quantum games across three dimensions: \textit{the perceivable dimension of quantum physics, the dimension of scientific purposes, and the dimension of quantum technologies}. We then further reflect on the definition of quantum games and its implications. While motivations behind developing quantum games have typically been educational or academic, themes related to quantum physics have begun to be more broadly utilised across a range of commercial games. In addition, as the availability of quantum computer hardware has grown, entirely new variants of quantum games have emerged to take advantage of these machines' inherent capabilities, \textit{quantum computer games}Comment: 8 pages, from which 1.5 pages of references, 11 figures, one table, presented in the IEEE Conference on Games 202